Silicon-carbon composite for lithium-ion battery anodes

Abstract

Silicon-carbon composite structures include silicon entities occupying pores in a carbon black support, where the carbon black support has a ratio of OAN:BET surface area in the range of 1 to 10, and a silicon mass per 100 g of carbon black less than or equal to 0.75 OAN. The silicon-carbon composite can have a carbon overcoat. The silicon-carbon composite structures can be prepared by CVD techniques or mechanical mixing and can be used in LIB anodes.

Description

[0001] Cross-references to related applications

[0002] This application claims the rights of U.S. Provisional Application No. 63 / 622,276, filed January 18, 2024, U.S. Provisional Application No. 63 / 569,448, filed March 25, 2024, U.S. Provisional Application No. 63 / 573,919, filed April 3, 2024, and U.S. Provisional Application No. 63 / 631,030, filed April 8, 2024, pursuant to 35 USC 119, the disclosures of which are incorporated herein by reference in their entirety. Background Technology

[0003] Lithium-ion batteries (LIBs) are a common source of electrical energy for many applications, from electronic devices to electric vehicles. A typical LIB includes a negative electrode and a positive electrode, arranged to allow lithium ions and electrons to move to and from the electrodes during charging and discharging. An electrolyte solution in contact with the electrodes provides a conductive medium in which ions can move. To prevent direct reactions between the electrodes, ion-permeable membranes are used to physically and electrically isolate the electrodes. During operation, electrical contact with the electrodes allows electrons to flow through the device to provide power, and lithium ions move from one electrode to another via the electrolyte.

[0004] Most commercially available lithium-ion batteries have an anode containing graphite, a material that can bind lithium through an intercalation mechanism. Typically, lithium is added to the graphite anode during charging cycles and removed when the battery is used. Other anode materials besides graphite, or those used as alternatives to graphite, include lithium titanate, tin oxide, silicon (Si), and SiO2. x (where x is typically 1.04, 1.06, etc.).

[0005] Silicon has attracted attention due to its relatively low cost, high abundance, environmentally friendly properties, and, importantly, its high energy density. While silicon can improve the energy density of LIB anodes, it also presents significant challenges. For example, silicon undergoes significant expansion and contraction during charge and discharge cycles, leading to reduced cycle lifetime and decreased energy density after cycling. Summary of the Invention

[0006] Therefore, there is a need for materials and technologies that can address at least some of the problems encountered when designing silicon-containing anodes. Silicon-carbon composites can solve some of these problems, where silicon is present in the pores or cavities of a carbon structure (e.g., a carbon black structure) that acts as a carrier or "scaffold" because it supports and contains the silicon.

[0007] In many respects, this disclosure relates to materials comprising carbon and silicon, and to anodes and batteries containing such materials. Other aspects of this disclosure relate to techniques for manufacturing silicon-carbon materials that can be used in LIBs or other applications.

[0008] In one embodiment, this disclosure is characterized by a silicon-carbon composite in which the carbon black support can accommodate the expansion and contraction of silicon entities (e.g., silicon nanoparticles) within its pores as Li diffuses in and out of the anode during each cycle. For example, the silicon-carbon composite disclosed herein may comprise a carbon black support and silicon within the pores of the carbon black support, wherein the ratio of OAN (oil adsorption value):BET (Brunauer-Emmett-Teller surface area) of the carbon black support is in the range of 1 to 10, wherein OAN is measured by ASTM D2414-23A and reported in ml / 100g carbon, and BET is measured by ASTM D6556-21, and the mass (in gf) of silicon per 100g carbon black support is less than or equal to 0.75. OAN. Silicon-carbon composites with these characteristics can improve the performance of LIBs. For example, balancing the OAN (which can be related to the void or pore volume in the carbon black support) with the amount of silicon in the pores allows for the volume expansion of silicon without leaving too much space to reduce energy density. Furthermore, balancing the OAN to BET ratio minimizes the formation of a solid electrolyte interface (SEI) caused by the contact between the electrolyte and the carbon black support. SEI reduces the amount of lithium in the LIB, and thus can reduce energy capacity.

[0009] In some embodiments, the silicon-carbon composite can be prepared by exposing the carbon black support to the silicon-containing precursor at a temperature sufficient to decompose the precursor and deposit silicon within the pores of the carbon black particles. In other embodiments, the silicon-carbon composite can be prepared by mechanically combining the carbon black support with silicon nanoparticles to form the silicon-carbon composite.

[0010] Porous carbon supports may be composed of, substantially composed of, or contain carbon black (CB). In specific embodiments, the carbon support is a CB entity formed from CB aggregates held together by various means, such as covalent bonds generated by graphitization, bonding with polymeric or inorganic binders, van der Waals forces, hydrogen bonds, electrostatic forces, or other substances (e.g., metal oxides used to bond the aggregates together). In some embodiments, porous carbon supports may be composed of, substantially composed of, or contain graphite. In some embodiments, porous carbon supports may be composed of a combination of graphite and carbon black, substantially composed of a combination of graphite and carbon black, or contain a combination of graphite and carbon black.

[0011] Some techniques that can be used to prepare silicon-carbon composites involve heating a Si-containing precursor to a sufficiently high temperature to decompose the precursor and deposit elemental Si within a carbon support. For example, in one embodiment, silicon is introduced via chemical vapor deposition (CVD) using a silane-type precursor.

[0012] Carbon black supports can be prepared by pulverizing CB pellets before, during, or after the introduction of silicon entities. In addition to CB, the pellets and / or supports may contain other components such as binders, single-walled and / or multi-walled carbon nanotubes, and / or metal oxides, to name a few.

[0013] Typically, the size of the starting particles will be larger than the size of the porous carbon support used to prepare the silicon-carbon composite structure. For example, the starting particles can be larger than 100 micrometers, larger than 500 micrometers, or larger than 1 millimeter (mm). In one example, the size of the starting particles is in the range of about 100 micrometers to about 1 mm or greater.

[0014] For example, carbon black supports obtained by jet milling CB pellets can have a size of about 1 to about 25 micrometers. Finished silicon-carbon structures can have particle sizes in the range of about 1 to about 25 micrometers. In one example, silicon-carbon composite structures for LIB applications have sizes between about 1 and about 25 micrometers, for example, a D50 volumetric particle size in the range of 1 to 25 micrometers or 5 to 25 micrometers.

[0015] For example, in some embodiments, the carbon support and / or the granules used to prepare it are heat-treated to graphitize the CB.

[0016] While it is important for carbon supports to provide sufficient void volume for silicon expansion during lithiation, allowing too much void volume represents wasted space that could otherwise be filled by the silicon entity. Therefore, further embodiments seek to balance the need for sufficient void volume to accommodate both the silicon entity itself and its expansion, while also maximizing the amount of silicon and thus maximizing the energy density of the composite.

[0017] The available empty volume in the carbon black support can be roughly estimated by the oil adsorption value (OAN). In many respects, this disclosure is characterized by porous carbon supports with an OAN in the range of 32 to 400 ml / 100 g carbon, for example, about 200 to about 300 ml / 100 g carbon.

[0018] The illustrative silicon-carbon composite will contain sufficient carbon to form a porous carbon support framework, which is interconnected to impart strength and conductivity. The amount of silicon is important for producing the desired high energy density. In one embodiment, the mass ratio of carbon to silicon in the silicon-carbon material is about 1:1. More typically, the mass ratio of carbon to silicon ranges from about 20:80 to about 80:20, or from about 40:60 to about 60:40.

[0019] Silicon-carbon composites containing silicon entities deposited or permeated within a porous carbon support can be used as additives in LIB applications. However, in such an environment, the potential formation of a solid electrolyte interface (SEI) can lead to a reduction in the amount of Li in the system, thereby decreasing energy capacity.

[0020] One approach to addressing this challenge relies on reducing the surface area of ​​the CB, for example, by selecting CBs with larger primary CB particles. In some instances, the CBs used have surface areas ranging from 3.2 to 400 m². 2 / g, for example 80 to 130m 2 / g of BET surface area.

[0021] Another approach involves maintaining a high surface area of ​​the carbon support (e.g., carbon black, graphite, or a combination of both) and the silicon loaded on the carbon (thus protecting the interior of the silicon-carbon composite entity). In a particular instance, access to the inner surface regions of the carbon and silicon is blocked by sealing the pores at the surface of the silicon-carbon structure. Sealing the surface pores can be accomplished through one or more covering operations. For example, the pores can be sealed or “closed” by covering with silicon, silicon oxide, and / or carbon. In one embodiment, the process is performed sequentially, for example, first closing the surface pores with silicon and then covering the entire entity with carbon. In many embodiments, silicon sealing is performed after the silicon entity (e.g., silicon nanoparticles) is deposited into the porous carbon support. Carbon covering can be performed by CVD using a suitable carbon-containing precursor (e.g., propylene). The apparent surface area (the internal surface area of ​​the undisturbed particles) can be, for example, less than 30 m². 2 / g, less than 25m 2 / g, less than 20m 2 / g, less than 15m 2 / g, less than 10m 2 / g, less than 5m 2 / g, or less than 2m 2 / g.

[0022] Implementing embodiments of the present disclosure presents numerous benefits. For example, using CB can bring attractive mechanical properties, electrical conductivity, and electrochemical compatibility with Li-ion battery chemicals at a relatively low cost. Using fine graphite particles (e.g., particles with a particle size less than or equal to 1 micron) utilizes relatively abundant and low-cost materials. Adding silicon (e.g., a structure (particle) with a carbon:silicon ratio of 50:50) to the silicon-carbon composite as described herein can contribute a large amount of energy to the electrode because silicon has a high energy density compared to graphite. In addition to having a higher energy density than graphite, silicon can be a cost-effective component, widely available, and environmentally friendly. In some cases, the silicon employed is provided by an easily accessible dry source (e.g., silane gas (SiH4)).

[0023] Starting materials such as CB pellets can be a cost-effective source for preparing porous carbon supports. The pellets can be customized or can be commercially available with the desired CB specifications. In some cases, the pellets have been heat-treated and graphitized, streamlining the processes described herein.

[0024] Closing the pores in the silicon-carbon composite can block external reagents from reaching the interior of the product structure. The protective layer can prevent the high-surface-area CB particles in the product structure from contacting the battery electrolyte and generating a solid electrolyte interface (SEI). Coating the silicon-carbon composite structure (e.g., with a carbon layer, a silicon layer, or a silicon suboxide (SiO x , 0 < x < 2) layer) can protect the high-surface-area CB and high-surface-area silicon within the composite from direct contact with the LIB electrolyte, thereby reducing any irreversible absorption of silicon or minimizing the formation of SEI. In some implementations, the surface pores are closed by silicon before carbon coating, thereby blocking the penetration of carbon-containing precursors and any deposition of the carbon coating material inside the composite. The pores closed by silicon can also indicate that sufficient Si has been deposited. The carbon coating can reduce the surface energy of the agglomerates, which can lead to reduced water molecule adsorption, resulting in easier processability and higher performance.

[0025] The above and other features of the present disclosure, including various details of the construction and combination of components and other advantages, will now be described more specifically with reference to the accompanying drawings and pointed out in the claims. It should be understood that the specific methods and devices embodying the present disclosure are shown by way of illustration and not as a limitation of the present disclosure. The principles and features of the present disclosure can be employed in various and numerous embodiments without departing from the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In the drawings, reference numerals refer to the same parts in different views. The drawings are not necessarily to scale; rather, emphasis is placed on illustrating the principles of the present disclosure. In the drawings:

[0027] Figure 1 The percentage volume-weighted PSD (particle size distribution) of Malvern AeroS dry powder from three different batches of commercial CB is presented.

[0028] Figure 2 This is a schematic diagram of a carbon black carrier;

[0029] Figure 3 This is a schematic diagram of a silicon-carbon composite structure (particles), in which the carbon black carrier contains silicon entities, such as silicon nanoparticles.

[0030] Figure 4 These are scanning electron micrographs of silicon-carbon composite particles with a size range of approximately 1-25 micrometers;

[0031] Figure 5 The image shows a scanning electron micrograph of silicon-carbon composite particles, revealing a single porous structure of silicon-carbon loaded with deposited silicon.

[0032] Figure 6A and 6B These are scanning electron micrographs of silicon-carbon composite particles (at different magnifications), showing silicon (brighter) nanoparticles and carbon with a size of about 10 nanometers on the surface;

[0033] Figure 7 This is a schematic diagram of silicon-carbon composite particles, which are covered by silicon deposited on the surface of the composite particles.

[0034] Figure 8 This is a schematic diagram of a silicon-carbon composite material covered by carbon deposited on the surface of composite particles.

[0035] Figure 9 This is a schematic diagram of silicon-carbon composite particles whose surface is covered with silicon and carbon.

[0036] Figure 10 This is a schematic diagram of a covered silicon-carbon composite containing graphite, carbon black, carbon nanotubes, and silicon nanoparticles.

[0037] Figure 11 This is a series of graphs comparing the performance of composites prepared by mechanical mixing of silicon and carbon components, the performance of composites prepared by silicon infiltration using CVD, and the performance of control materials that do not contain silicon. Detailed Implementation

[0038] This disclosure will now be described more fully below with reference to the accompanying drawings, in which illustrative embodiments of the disclosure are shown. However, this disclosure may be implemented in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of this disclosure to those skilled in the art.

[0039] As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. Furthermore, all conjunctions used should be understood in the most inclusive sense possible. Thus, the word “or” should be understood as having the definition of logical “or” rather than logical “exclusive OR”, unless the context explicitly states otherwise. Additionally, unless explicitly stated otherwise, the singular form and the articles “a,” “an,” and “the” are also intended to include the plural form. It will be further understood that, when used in this specification, the terms “comprising,” “including,” “contains,” and / or “components” specify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Furthermore, it should be understood that when an element comprising a component or subsystem is referred to and / or shown as connected or coupled to another element, it may be directly connected or coupled to the other element, or there may be intermediate elements present.

[0040] It will be understood that although terms such as “first” and “second” are used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. Therefore, without departing from the teachings of this disclosure, the elements discussed below may be referred to as second elements, and similarly, second elements may be referred to as first elements.

[0041] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It will be further understood that terms (such as those defined in common dictionaries) shall be interpreted as having a meaning consistent with their meaning in the context of the relevant field and shall not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0042] This disclosure generally relates to electrochemical cell batteries, used in many cases as batteries, such as rechargeable LIBs. Typically, LIB batteries are named according to the acronym of the electroactive material (often an intercalation compound) used to form the cathode. The embodiments described herein can be practiced or applied to various types of lithium-ion batteries known in the art, such as LCO (lithium cobalt oxide), LMO (lithium manganese oxide), NCM (lithium nickel cobalt manganese oxide), NCA (lithium nickel cobalt aluminum oxide), LCP (lithium cobalt phosphate), LFP (lithium iron phosphate), LMFP (lithium manganese iron phosphate), LFMP (lithium manganese iron phosphate), LFSF (lithium iron fluorosulfate), or LTS (lithium titanium sulfide), to name just a few, or future LIBs.

[0043] In one aspect, this disclosure relates to materials containing silicon and carbon, such as silicon-carbon composites. Composites or composite particles (also referred to herein as “composite structures” or “composite entities”) typically comprise a carbon component and a silicon component (e.g., silicon entities, such as silicon nanoparticles) made of a porous carbon support (e.g., a carbon black support).

[0044] The relative amounts of silicon and carbon present in the composite can vary depending on, for example, the specific end use or other factors. In some embodiments, this disclosure addresses not only the energy density improvement associated with the presence of silicon in the LIB anode, but also the challenges posed by the high expansion and contraction of silicon during cycling.

[0045] Silicon's high theoretical specific capacity (approximately 4,200 mAh / g, based on the formation of a Li₂₂Si₅ alloy) is about 10 times higher than that of conventional carbon-based anodes (typically about 372 mAh / g for graphite). (For pristine silicon, the capacity is 3,600 mAh / g.) A 50:50 silicon-carbon composite will introduce a structure into the anode with an energy density five times that of graphite.

[0046] However, during operation, Li absorption can lead to silicon volume expansion of up to 400%, with significant volume contraction occurring during lithium extraction. Even when silicon is typically not fully lithiated during cycling, the volume expansion can exceed twice its initial volume.

[0047] In some of the silicon-carbon materials described herein, porous carbon supports (scaffolds or matrices) not only contain silicon entities, but also contain the expansion and contraction that characterizes these entities during cycling.

[0048] To illustrate, the close packing of carbon spheres provides about 25% open volume, a value too low to contain both enough silicon for the required energy density and enough free space for its volume expansion. In contrast, the void volume inside some materials (e.g., many high-structure carbon blacks) can be five times or more than the volume of the material itself (e.g., carbon black).

[0049] However, allowing too much void volume may represent wasted opportunities for Si loading. Therefore, there exists an optimal void volume that is sufficient to accommodate the silicon itself and its expansion during cycling without leaving excessive unoccupied volume (which would reduce the energy density in the resulting anode).

[0050] Consider the following mass-to-volume ratio: 33 vol% silicon, used to provide higher energy density for the final composite material; 33 vol% carbon, used to form a porous support framework that is interconnected to impart strength and conductivity; and 33 vol% open space, with the available 33 free volume% not allowing for full Si expansion of up to 400% during Li absorption.

[0051] In contrast, when sufficient void volume is provided, deposited silicon allows fully lithiated silicon to fill all void volumes, resulting in a silicon-carbon composite that, approximately, at 400% expansion, consists of 20 vol% carbon and 80 vol% fully lithiated silicon, completely filling the void spaces, or 20 vol% unexpanded silicon. Based on density, this corresponds to 50 wt% Si in the silicon-carbon composite, with a silicon:carbon ratio of 1:1.

[0052] Therefore, some silicon-carbon composites described herein have a silicon to carbon mass ratio in the range of about 40:60 to about 60:40. In specific embodiments, the silicon to carbon mass ratio is about 50:50, a ratio that provides sufficiently high energy density due to the relatively high silicon content. In other embodiments, the silicon to carbon mass ratio of the silicon-carbon composites described herein can be in the range of about 20:80 to about 80:20, about 30:70 to about 70:30, about 40:60 to about 60:40, about 45:55 to about 55:45, about 50:50, or any and all ranges and subranges thereof. While other ratios can be chosen, a much higher silicon content can result in insufficient silicon loading in the carbon structure. On the other hand, a much lower silicon content can result in an increased carbon black surface area and a reduced energy density due to the lower silicon content.

[0053] In one embodiment, the carbon component in the silicon-carbon material described herein consists of, substantially consists of, or comprises carbon black (CB), graphite, or a combination of carbon black and graphite.

[0054] Typically, CBs exist as aggregates, which are formed from primary CB particles. In most cases, the primary particles do not exist independently of the CB aggregates. While the primary particles can have an average diameter ranging from about 10 nanometers (nm) to about 50 nm (e.g., about 10 nm to about 15 nm; about 10 nm to about 20 nm; about 10 nm to about 25 nm; about 10 nm to about 30 nm; or about 10 nm to about 40 nm), the aggregates can be quite large. CB aggregates have fractal geometry and are often referred to in the art as CB “particles” (not to be confused with the “primary particles” discussed above). Typically, the aggregates have a significant internal volume corresponding to the space between the primary particles within the aggregate. CB aggregates can form even larger structures, referred to herein as CB “agglomerates.”

[0055] Many types of carbon black are produced in furnace reactors by pyrolyzing hydrocarbon feedstocks (FS) with hot combustion gases to produce combustion products containing particulate carbon black. The properties of a given carbon black often depend on the manufacturing conditions and can be changed or modified, for example, by variations in temperature, pressure, FS, residence time, quenching temperature, production rate, and / or other parameters. Carbon black can also be produced using acetylene-based processes.

[0056] As is known in the art, CB can be described by certain properties determined according to procedures well known in the art (typically standardized schemes). For example, CB can be characterized by its Brunauer-Emmett-Teller (BET) surface area, for example, measured according to ASTM D6556-21; its oil absorbent value (OAN), for example, determined according to ASTM D 2414-23A; or its statistical thickness surface area (STSA) (a property that can be determined according to ASTM D 6556-21).

[0057] For a given CB, in some cases, it may also be attractive to specify the ratio of its STSA to its BET surface area (STSA:BET ratio).

[0058] The crystal domains of CB can be obtained through L a Grain size is used for characterization, such as by Raman spectroscopy. a Defined as 43.5 × (area of ​​G-band / area of ​​D-band). Grain size can indicate the degree of graphitization, where higher L... a The value is correlated with a higher degree of graphitization. L a The Raman measurements are based on Gruber et al.'s "Raman studies of heat-treated carbonblacks". Carbon Vol. 32 (7), pp. 1377-1382, 1994, which is incorporated herein by reference. The Raman spectrum of carbon includes approximately 1340 cm⁻¹. -1 and 1580cm -1 The two main "resonance" bands at this point are designated as "D" and "G" bands, respectively. The D band is generally considered to be attributed to disordered spp. 2 Carbon, while the G-band is attributed to graphite or "ordered" sp. 2 Carbon. Using empirical methods, the G / D band ratio is compared with the L band measured by X-ray diffraction (XRD). a They are highly correlated, and regression analysis provides an empirical relationship:

[0059] L a =43.5×(area of ​​G band / area of ​​D band),

[0060] Where L a by Calculation. Therefore, a higher L a The value corresponds to a more ordered crystal structure.

[0061] Crystal domains can be accessed via L c Grain size was used for characterization. L was determined by X-ray diffraction using a PANalytical X'Pert Pro (PANalytical BV) spectrometer. c Grain size, the X-ray diffractometer uses a copper tube, tube voltage of 45kV, and tube current of 40mA. The carbon black particle sample is loaded into a sample support (an accessory of the diffractometer) and diffracted at an angle of 10° to 80° (2) at a speed of 0.14° / min. Measurements were performed within the specified range. Peak positions and full width at half maximum (FWHM) values ​​were calculated using the diffractometer software. Lanthanum hexaboride (LnO) was used for measurement angle calibration. a B6) was used as the X-ray standard. From the obtained measurements, L was determined using the Scherrer equation. c Grain size: , where K is the shape factor constant (0.9); yes (1.54056 The wavelength of characteristic X-rays; It is the half-peak width in radians; and By taking the position of the measured angle peak (2) The carbon black carrier is determined by half of the carbon black carrier's weight. In some embodiments, the carbon black carrier has a weight of less than or equal to 42, 40, 35, 30, 25, 20, or 14. L c Grain size. In some embodiments, the L of the carbon black carrier...c Grain sizes are 14 to 42, 14 to 40, 14 to 35, 14 to 30, 14 to 25, 20 to 42, 20 to 40, 20 to 35, 20 to 30, 25 to 42, 25 to 40, 25 to 35, 30 to 42, 30 to 40, 35 to 42, 35 to 40 Within the range of, or any and all ranges or subranges within, because these L c This indicates that the carbon black carrier underwent heat treatment at a temperature below 1800 degrees Celsius.

[0062] Surface cleanliness can be described by the surface energy (SEP) of CB, which is a property that can be determined by dynamic vapor (water) adsorption (DVS) or water spreading pressure (as described, for example, in U.S. Patent No. 10,886,535B2 to Korchev et al., issued January 5, 2021, and incorporated herein by reference). Lower surface energy typically corresponds to a lower surface concentration of oxygen-containing groups.

[0063] The mean pore diameter and pore volume can be determined according to the technique (BJH method) described in EP Barrett, LG Joyner, PPHalenda, J. Am. Chem. Soc. 1951, 73, 373-380.

[0064] Other techniques that can be used to study carbon (CB) include Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). FTIR spectroscopy is particularly useful for determining the properties of surface functional groups, while SEM / TEM techniques help visualize the size and morphology of particles. XPS is frequently used to determine the elemental composition of materials, and TGA can provide information about the decomposition and oxidation characteristics of carbon.

[0065] Malvern laser diffraction techniques can be used to measure particle size and particle size distribution, such as D50 volumetric particle size. Malvern instruments measure particles within a specific range by measuring the intensity of light scattered as a laser beam passes through a dispersed granular sample. Malvern instruments operated with flowing gas can approximate conditions in a fluidized bed, where the flowing gas suspends agglomerates. The Malvern laser diffraction technique used in this paper to test the material was performed using a Mastersizer 3000 with an Aero S attachment (available from Malvern Panalytical), following the procedures in the Mastersizer 3000 Basic Guide published on August 6, 2024. The equipment settings were configured according to the table below. Before adding the sample, a 2 mm diameter sieve was installed on the Aero S hopper. During the measurement, the Aero S feed rate was manually adjusted to ensure an average shading of approximately 3%.

[0066]

[0067] In some embodiments, the D50 volumetric particle size of the silicon-carbon composite can be greater than 1 micrometer, greater than 5 micrometers, greater than 6 micrometers, greater than 7 micrometers, greater than 8 micrometers, greater than 9 micrometers, greater than 10 micrometers, or greater than 15 micrometers. In some embodiments, the D50 volumetric particle size of the silicon-carbon composite can be in the range of 1 to 25 micrometers, 1 to 20 micrometers, 1 to 15 micrometers, 5 to 25 micrometers, 5 to 20 micrometers, 5 to 15 micrometers, 6 to 25 micrometers, 6 to 20 micrometers, 6 to 15 micrometers, 7 to 25 micrometers, 7 to 20 micrometers, 7 to 15 micrometers, 8 to 25 micrometers, 8 to 20 micrometers, 8 to 15 micrometers, 9 to 25 micrometers, 9 to 20 micrometers, 9 to 15 micrometers, 10 to 25 micrometers, 10 to 20 micrometers, or any and all ranges and subranges thereof.

[0068] In some embodiments, the carbon black support used in the silicon-carbon materials described herein is a rigid aggregate of CB aggregates. The porosity of such aggregates corresponds to the porosity within the primary particles, the space within the aggregate structure (formed by the primary particles), and the space between the aggregates. The pores within the primary particles are smaller than the size of the primary particles, typically less than 10 nm. These small pores have a small total pore volume percentage and cannot load a large amount of silicon by mass fraction. The inter-aggregate porosity (the pores between aggregates within the aggregate) can range from about 10 nm to about 500 nm, while the intra-aggregate porosity (the pores between primary particles within the aggregate) can range from about 10 nm to about 500 nm.

[0069] The total porosity of CB aggregates can be determined by taking into account the oil adsorption value (OAN), which characterizes porous carbon supports. OAN represents the number of cubic centimeters of dibutyl phthalate (DBP) or paraffin oil absorbed by 100 g of carbon black under specific conditions according to ASTM D-2414-23A.

[0070] As mentioned above, an important objective of LIB anode applications is to provide sufficient empty volume for silicon expansion during cycling, while maximizing the silicon occupancy of the pores, thereby maximizing the energy density of the resulting electrode.

[0071] Using OAN to approximate the amount of void volume in carbon agglomerates can help determine the theoretical maximum silicon loading that can be accommodated within the pores at full lithiation. In one example, approximately 45 cm³ of void volume exists per 100 g of carbon. 3 The volume of carbon, and OAN can be used to convert it to a volume percentage of carbon. Theoretically, all the remaining volume of porous carbon can be filled by lithiated silicon (leaving no space for the electrolyte). Considering that fully lithiated silicon (which can expand by about 400%) gives the maximum permissible volume of silicon. Based on density, this can be converted to a maximum Si weight percentage (wt%).

[0072] Commercially available carbon substrates (CBs) offer a wide range of properties, including various values ​​for the OAN (Optical Angle of Representation). In one embodiment, the silicon-carbon composites described herein are prepared using CBs with an OAN corresponding to a relatively high Si capacity. For example, a CB with an OAN of 216 ml / 100 g (e.g., LITX HP) allows for 55 wt% Si, which is close to the desired 50:50 silicon-carbon product weight percentage. Table 1 below compares two porous carbon supports using different CB specifications, showing that porous carbon supports characterized by higher OAN will have a higher Si capacity than those available when using CBs with lower OAN.

[0073] Table 1

[0074]

[0075] More generally, 200 to 300 ml / cm 3 The OAN value gives approximately 2-3 cm² per gram of carbon aggregate. 3 The volume. Considering 2.26 g / cm³ 3 With a carbon density such that CB can provide enough space not only to accommodate the silicon entities themselves, but also to accommodate the expansion and contraction of these entities during cycling.

[0076] Therefore, in specific embodiments of this disclosure, the OAN of the porous carbon support (before any silicon permeates into the support) is in the range of about 32 to about 400 ml / 100 g carbon, for example, 32 to: 250, 275, 300, 325, 350, 375, 400ml / 100g charcoal; 50 to: 250, 275, 300, 325, 350, 375, 400ml / 100g charcoal; 100 to: 250, 275, 300, 325, 350, 375, 400ml / 100g charcoal; 150 to: 250, 275, 300, 325, 350, 375, 400ml / 100g charcoal; 200 to: 220, 240, 260, 280, 300, 325, 350, 375, 400ml / 100g charcoal; or, 220 to: 240, 260, 280, 300, 3... 25, 350, 375, 400 ml / 100g carbon; or 240 to: 260, 280, 300, 325, 350, 375, 400 ml / 100g carbon; or 260 to: 280, 300, 325, 350, 375, 400 ml / 100g carbon; or 280 to: 300, 325, 350, 375, 400 ml / 100g carbon, 300 to: 325, 350, 375, 400 ml / 100g carbon, 325 to: 350, 375, 400 ml / 100g carbon, or 350 to: 375, 400 ml / 100g carbon, or any and all ranges and subranges thereof.

[0077] Another factor to consider is the surface area (SA) of the porous carbon support. During operation, the carbon can come into contact with the electrolyte used in the LIB, potentially leading to the formation of a solid electrolyte interphase (SEI). The SEI absorbs Li, thereby reducing the amount of Li in the system and decreasing the energy capacity.

[0078] For carbon with a large surface area, SEI formation can be more pronounced. For example, a carbon with a surface area of ​​250 m²... 2 Carbon black at a concentration of / g can introduce a large surface area into the anode. In contrast, graphite has a much lower surface area, for example, very roughly about 1m². 2 / g (for illustrative purposes). Based on 1g, using 0.5g CB (with 250m) 2 Replacing 0.5g of graphite with / g of surface area increases the surface area by 125m². 2 / g.

[0079] Various measures can be taken to address this challenge. One approach involves reducing the surface area, for example, by using larger primary particles (which typically provide a lower surface area).

[0080] Therefore, one implementation uses a BET surface area of ​​approximately 3.2 to approximately 400 m². 2 Porous carbon supports in the range of / g, for example, 3.2 to: 100, 150, 200, 250, 300, 350, 400m 2 / g, 50 to: 100, 150, 200, 250, 300, 350, 400m 2 / g, 80 to: 90, 100, 120, 150, 200, 250, 300, 350, 400m 2 / g; or 90 to: 100, 110, 120, 130, 150, 200, 250, 300, 350, 400mg 2 / g; or 100 to: 110, 120, 130, 150, 200, 250, 300, 350, 400mg 2 / g; or 110 to: 120, 130, 150, 200, 250, 300, 350, 400mg 2 / g; or 120 to: 130, 150, 200, 250, 300, 350, 400mg 2 / g; 150 to: 200, 250, 300, 350, 400m 2 / g; 200 to: 250, 300, 350, 400m 2 / g; 250 to: 300, 350, 400m 2 / g, or any and all ranges and subranges thereof. In one instance, the carbon support is composed of BET of approximately 100m. 2 / g of CB composition.

[0081] In some implementations, the carbon within (within) the porous carbon black support is graphitized to increase its crystallinity (a property that can be measured by Raman spectroscopy, as described above). For commercial carbon black, graphitization is often carried out after CB manufacturing, in a heat treatment process, typically at relatively high temperatures. Possible heat treatment techniques are described, for example, in U.S. Patent Nos. 9,287,565, 10,135,071, and 10,971,730. The entire contents of these patents are incorporated herein by reference.

[0082] In certain instances, the CB used in the porous carbon black support described herein is graphitized CB. In other instances, the CB is graphitized at some point in the process used to prepare the silicon-carbon composite material described herein. Ungraphitized CB may also be used.

[0083] As crystallinity increases, heat treatment (characterized by parameters such as heating temperature, the time interval used, and the method for heating to and / or maintaining a certain temperature) may result in a reduction or elimination of porosity within the primary carbon particles. This may be advantageous in some cases where lower SA is desired.

[0084] Without heat treatment and graphitization, the primary particles forming CB aggregates can themselves contain porosity. If present, the porosity within the primary particles contributes to the total porosity of the aggregates, and this contribution is reflected in the higher surface area of ​​the porous carbon support. When heat treatment is not used and a lower surface area is required, carbon with no internal surface area is preferred.

[0085] In specific instances, the porous carbon black carrier contains metallic impurities at concentrations of less than 100, less than 50, less than 25, less than 10, or less than 5 parts per million (ppm). Typically, the levels of individual or collective inductively coupled plasma (ICP) metals such as cobalt, chromium, copper, manganese, nickel, and iron are not greater than 100, 50, 25, 10, or 5 ppm.

[0086] In many cases, the ash content is less than 0.1% by weight.

[0087] Some properties of the three different CB specifications (i.e., A, B, and C) that can be considered for the preparation of carbon black carriers are shown in Table 2 below.

[0088] Table 2

[0089]

[0090] Metals: Co, Cr, Cu, Mn, Ni.

[0091] In one embodiment, an adhesive is added to hold the carbon aggregates together and / or reinforce the carbon black carrier. In some embodiments, the adhesive may include, but is not limited to, polyacrylic acid, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), other adhesives typically used for lithium-ion battery cathodes or anodes, or any combination thereof.

[0092] In some embodiments, the crystallinity of the CB or carbon black carrier is at least 22%, for example, from 23% to 55%, for example, in the range of about 23% to about 30, 35, 40, 45, 50, 55%; or about 30% to about 35, 40, 45, 50, 55%; or about 35% to about 40, 45, 50, 55%; or about 40% to about 45, 50, 55%; or about 45% to about 50, 55%.

[0093] In one example, the L of the CB or carbon black carriera The grain size is at least 14. For example, from 14 up to 50 For example, CB's L a The grain size can be approximately 14. To: approximately 20, approximately 30, approximately 40, approximately 50 Approximately 17 To: approximately 20, approximately 30, approximately 40, approximately 50 Or about 20 To about 30, to about 40, to about 50 Or about 30 To: Approximately 40, Approximately 50 Or approximately 40 to approximately 50 .

[0094] Examples of commercially available carbon blacks (CBs) that can be used to prepare the silicon-carbon materials described herein include LITX® HP, high-purity carbon black, Denka black from Denka, Japan, or other acetylene blacks that can be granulated or ungranulated and then used as described herein. Carbon black from Imerys may also be used.

[0095] In some implementations, the carbon black carrier consists of a mixture of carbon black (blended), a mixture of essentially carbon black (blended), or a mixture containing carbon black (blended). The CB type in the blend can vary in terms of its BET, OAN, and / or other properties.

[0096] Further implementations involve carbon black carriers comprising carbon nanotubes (CNTs) combined with carbon nanotubes (CNTs) (provided as a single CNT specification or as a blend), the carbon nanotubes being a material that can impart good electrical, thermal, and mechanical properties. When used in lithium-ion battery electrodes, CNTs can enhance battery performance, such as power, cycle life, and / or energy density.

[0097] As is known in the art, CNTs are carbonaceous materials, typically hydrophobic, and characterized by at least one sp... 2 - Hybridized carbon atoms bond together to form a honeycomb lattice, which forms cylindrical or tubular structures. Carbon atoms in carbon nanotubes are arranged in hollow (e.g., cylindrical) structures, the length of which is typically greater than the radial diameter. In many cases, CNTs are characterized by a high aspect ratio, where the length is typically greater than 100 times the diameter.

[0098] Both single-walled and multi-walled CNTs can be used, as well as mixtures of two or more different types of CNTs. Single-walled CNTs (SWCNTs) can be considered as sp. fullerenes. 2Hybridized carbon allotropes. The structure is a cylindrical tube comprising a six-membered carbon ring. Double-walled carbon nanotubes (DWCNTs) tend to exhibit properties similar to SWCNTs. Multi-walled CNTs (MWCNTs) have several tubes within a concentric cylinder. The number of these concentric walls can vary, for example, from 2 to 25 or more. Typically, MWNTs can have a diameter of 10 nm or greater, compared to 0.7 to 2.0 nm for typical SWCNTs.

[0099] Based on chirality, CNTs are classified into armchair-shaped, serrated, and chiral nanotubes.

[0100] CNTs can be characterized by properties such as length, diameter, aspect ratio, surface area (e.g., BET), bulk density, tap density, and particle size distribution (PSD). In many embodiments, the CNT material used has a CNT purity of 97% or higher. Typically, anionic, cationic, or metallic impurities are low, for example, in the parts per million (ppm) range. Often, CNTs do not require further additives to counteract van der Waals forces.

[0101] If present in a porous carbon support, CNTs can be identified and / or characterized by techniques such as electron microscopy, including, for example, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). In some cases, Raman spectroscopy and / or thermogravimetric analysis can be employed. For example, the number of walls present (if using MWCNTs) can be determined by transmission electron microscopy (TEM) at a magnification sufficient to analyze the number of walls in a particular case. Since CNTs are known to contain considerable amounts of catalyst and other residues, these substances can be detected by techniques such as SEM, TEM, inductively coupled plasma atomic emission spectrometry, or ICP-AES.

[0102] In many implementations, the CNTs used are conventional (also known as "ordinary," "pristine," or "fresh") CNTs, which are often supplied in individual forms, such as commercially manufactured, or, in some cases, custom-synthesized or processed. Commercially available CNT materials include, but are not limited to, those available from Cabot Corporation under the trade name ENERAMAX® carbon nanotubes, those available from CNano under the trade name FT, and those available from LG Chem under the trade name Lucan.

[0103] CNTs can be provided in any suitable amount, for example, determined and / or optimized through routine experiments. In one example, the amount of CNTs in the porous carbon support is from about 0.1 to about 10 wt%. In another example, the amount of CNTs in the porous carbon support is from about 1 to about 10 wt%. For illustration, the amount of CNTs can range from about 0.1 to about 1, 2, 3, 4, 5, 6, 7, 8 or 9 wt%; from about 1 to about 2, 3, 4, 5, 6, 7, 8 or 9 wt%; from about 2 to about 3, 4, 5, 6, 7, 8, 9 or 10 wt%; from about 3 to about 4, 5, 6, 7, 8, 9 or 10 wt%; from about 4 to about 5, 6, 7, 8, 9 or 10 wt%; from about 5 to about 6, 7, 8, 9 or 10 wt%; from about 6 to about 7, 8, 9 or 10 wt%; from about 7 to about 8, 9 or 10 wt%; from about 8 to about 9 or 10 wt%; from about 9 to about 10 wt%.

[0104] Porous carbon supports can have any suitable shape. The shape can be defined by grinding. For example, spheroidized supports can be obtained by gently grinding with a medium to round off sharp corners. This can be accomplished using a method similar to spheroidizing graphite used for anodes.

[0105] The carbon black support and silicon-carbon composite can have an average size or D50 volumetric particle size ranging from about 1 to about 25 micrometers. In one embodiment, the support has an average size of about 10 micrometers (μm), as measured by Malvern optical scattering of the entrained carbon black support. For example, the carbon black support can be dispersed in a flowing gas stream, the gas stream carrying the dispersed support and the volume observed by light scattering. As an example, Figure 1 The volume-weighted particle size distribution (PSD) of Malvern Aero S dry powder is shown for three different batches of CB samples at a feed pressure of 0.5 bar (average five replicate runs per sample).

[0106] D50 silicon-carbon composites and carbon black supports with a volumetric or average particle size of about 1 to about 25 micrometers, and particularly supports of about 5 to 10 micrometers, are compatible with typical LIB anode applications. Other advantages associated with the above size range include, but are not limited to, the ability to fluidize in fluidized beds used for chemical vapor deposition of silicon and / or carbon. Smaller volumes can be entrained out of the fluidized bed reactor, while larger volumes can result in a rough film in the anode layer and / or interfere with the coating processes used to fabricate the anode layer.

[0107] The carbon black carrier of the required size can be custom-made or commercially available.

[0108] In one example, one or more types of carbon black and optional CNTs are ground together to reduce their particle size and combined. In some cases, a binder (e.g., polyacrylic acid) may be used. The resulting mixture of carbon components and optional binder can then be formed into granules using techniques such as granulation or granulation using a granulator. In one example, the granules may be jet-milled to a suitable size (approximately 10 micrometers) to produce a carbon carrier structure.

[0109] In another example, the carbon support exhibiting the desired particle size distribution is obtained from readily available materials. For instance, the porous carbon support may be CB pellets or may be obtained from CB pellets, as further described below.

[0110] An illustrative schematic diagram of the carbon black carrier 10 is shown in Figure 2 middle.

[0111] In some embodiments, the carbon black carrier may also comprise graphite. Natural and artificial / synthetic graphite may be used, as well as combinations of different types of graphite. The graphite used may be characterized by one property, and in many embodiments, by more than one property, as further described below.

[0112] One important consideration in selecting suitable graphite materials is their purity. Graphite, especially natural graphite, often contains impurities such as potassium, sodium, aluminum, iron, calcium, magnesium, and / or silicate minerals. Since these substances can negatively impact battery performance, specific embodiments of the present invention utilize graphite with a purity of at least 99%, often at least 99.5%, or even at least 99.95%.

[0113] In contrast to conventional graphite used in LIB anode applications (which typically has a particle size of several micrometers, such as around 10 micrometers), many embodiments of the carbon support in the silicon-carbon composites described herein are characterized by porosity that can define and contain silicon particles, for example, 100 nm in size. Using graphite particles that are too large (as is typical in LIB anode graphite materials) will not provide sufficiently small porosity or sufficient pore volume between the graphite particles. Another factor to consider is the overall particle size of the resulting silicon-carbon composite. These considerations point to graphite materials with particle sizes no larger than, and often smaller than, about 1 micrometer.

[0114] In illustrative examples, the D50 volumetric particle size of graphite particles, as measured by the Malvern technique described above, is between about 0.1 and about 0.2, 0.4, 0.6, 0.8, or 1.0 micrometers; between about 0.2 and about 0.4, 0.6, 0.8, or 1.0 micrometers; between about 0.4 and about 0.6, 0.8, or 1.0 micrometers; between about 0.6 and about 0.8 or 1.0 micrometers; and between about 0.8 and about 1 micrometer.

[0115] Furthermore, unlike most spherical graphite particles used in LIB anode applications, many of the composites described herein comprise graphite particles that are typically irregularly shaped, exhibiting, for example, serrated edges, (sharp) corners, deep indentations, and / or prominent protrusions.

[0116] In certain embodiments, the graphite used (having a particle size no larger than about 1 micrometer and often irregularly shaped) is in the form of graphite “fine grains,” a byproduct of the manufacture of graphite anode LIB materials. To increase the packing density and thus achieve higher energy density, many manufacturing processes (e.g., aimed at producing graphite particles of about 10 micrometers) include an operation in which the graphite particles are “rounded” (to remove corners, jagged edges, rough spots, etc.) using a special grinder. The shredded graphite flakes produced during this operation constitute the graphite fine grains that can be used in the composites described herein.

[0117] Of the various sizes of cuts that can be obtained from graphite spheroidization, those in the range of about 0.1 micrometers to about 1 micrometer are of particular interest. Therefore, in many cases, the graphite grains chosen for preparing the composites are micrometers in size and smaller, but typically larger than 100 nm (or 0.1 micrometers). However, other sizes of cuts can be considered in some cases.

[0118] In some implementations, the fine particles used are obtained by processing purified graphite material, for example, purified graphite material used in the final rounding process to prepare ultra-high purity anode materials. In some cases, the graphite used is partially or completely coated with pitch-derived carbon; this coating step is standard for the synthesis of graphite anode materials.

[0119] Analytical techniques that can be relied upon to evaluate graphite (often in the form of fine graphite particles) in the complex include, but are not limited to, scanning electron microscopy (SEM); X-ray diffraction (XRD); and / or Raman spectroscopy. Impurity concentrations can be determined by inductively coupled plasma atomic emission spectrophotometry (ICP-AES).

[0120] In some embodiments, the carbon in the carbon support can be entirely graphite, or it can be a combination of graphite and carbon black and / or carbon nanotubes. For many applications, adding more graphite increases energy capacity. Adding more carbon nanotubes (CBs), especially CBs with high structure, provides greater pore volume. CBs can also have useful energy storage capacity. Adding more carbon nanotubes (CNTs) manages the expansion and contraction of Si and provides conductivity within the particles. As part of some preparation methods (described further below), fine particles can be aggregated (e.g., granulated) to produce carbon supports with a D50 volumetric particle size (e.g., about 10 micrometers) ranging from about 1 micrometer to about 25 micrometers.

[0121] In one embodiment, the carbon component present in the silicon-carbon composite may include graphite ranging from about 0 wt% to about 100 wt%; CB ranging from about 0 to about 100%; and CNTs ranging from about 0 to about 25 wt%. Other compositions may contain higher loadings of CB and / or CNTs with a correspondingly lower percentage of graphite. Many embodiments aim to achieve a balance between the increased porosity due to the increased amount of CB and / or CNTs and the gain capacity from the higher amount of graphite present in the composite.

[0122] In many embodiments, the carbon support, whether or not composed of carbon black, graphite, or a combination thereof, is porous. The void volume can be tailored to accommodate maximum Si loading while allowing for Si volume variations during cycling. The porosity of the carbon support can be influenced by the porosity of the component itself, the size of the particles used, their shape (smaller spherical particles are less likely to achieve dense packing), surface energy, and / or other factors.

[0123] The second component (silicon) in the composite has the form of a silicon entity present within the pores of the carbon support (e.g., inter-aggregate pores and / or intra-aggregate pores). In embodiments employing porous primary particles, the silicon entity may also occupy the pores within the primary particles.

[0124] As measured by SEM images, silicon entities can have a particle size no larger than about 150 nm, for example, no larger than about 125, 100, 80, 70, 60, 50, 40, 30, 20, or 10 nm. In some embodiments, the silicon entities are silicon nanoparticles, i.e., particles no larger than and often smaller than about 100 nm. For many applications, the size of silicon nanoparticles ranges from about 1 nm to about 100 nm. In specific instances, silicon nanoparticles are in the range of about 10 to about 20, 30, 40, 50 nm; or about 20 to about 30, 40, 50 nm; or about 30 to about 40, 50 nm; or about 40 to about 50 nm.

[0125] While larger particles can be used, choosing a size of 100 nm or less makes the silicon particles less prone to breakage as they expand and contract during cycling.

[0126] The silicon entities can be discrete entities disconnected from each other. There can also be connectivity between at least some silicon entities. In some cases, silicon initially forms a coating of nanoparticles within the internal pores of the support. This coating of silicon nanoparticles on the carbon forming the porous support can evolve during battery operation as Li enters and silicon material moves around. At higher silicon loadings, a continuous coating of silicon can be present, at least partially, on the carbon. This coating can eventually form small silicon particles or can remain as a coating during subsequent processing and / or battery operation.

[0127] Silicon can be crystalline or amorphous, depending on the process used to incorporate it into a porous carbon support. For example, amorphous silicon nanoparticles can be produced by silicon CVD using silanes.

[0128] A schematic diagram of the silicon entity 12, which is a structure supporting carbon aggregates forming a porous carbon support 10, is shown in the figure. Figure 3 middle.

[0129] Silicon can be introduced (infiltrated or deposited) into porous carbon supports through various methods. One technique relies on chemical vapor deposition (CVD). In this approach, the carbon support is exposed to a silicon precursor (e.g., silane (SiH4) gas) at a relatively high temperature (e.g., 500–600 °C) for a sufficient time (often 1 to 10 seconds) to deposit silicon within the porous carbon support and produce a silicon-carbon composite at the desired silicon-carbon ratio (e.g., approximately 50:50 by mass). Figure 4 , 5 Scanning electron micrographs of carbon-silicon composite particles are shown in Figures 6A and 6B, in which silicon nanoparticles are deposited onto a porous carbon support by CVD using a silane gas precursor.

[0130] Other Si-containing precursors that can be used to generate silicon components include silicon tetrachloride or tetrachlorosilane (SiCl4), trichlorosilane (SiCl3H), and silane (Si2Cl6), to name just a few. Some Si-containing precursors may require higher deposition temperatures.

[0131] As is known in the art, the precursor can be provided in a carrier gas (e.g., hydrogen or nitrogen).

[0132] CVD processes can be performed continuously, semi-continuously, or in batch mode using suitable equipment (e.g., equipment designed for granular (powder) applications). Examples include, but are not limited to, fluidized beds, moving (entrained) beds, fixed beds, stirred beds, rotary tube furnaces, or other suitable reactors. In one instance, the CVD operation is performed for a duration (often at least 1 to 10 seconds) sufficient to deposit silicon within a porous carbon scaffold and produce a composite with the desired silicon-to-carbon ratio (e.g., a mass ratio of approximately 50:50). In some implementations, when using a fluidized bed, the minimum fluidization velocity is at least 0.1 cm / s, at least 0.5 cm / s, at least 1.0 cm / s, at least 2.0 cm / s, at least 3.0 cm / s, at least 4.0 cm / s, at least 5.0 cm / s, not exceeding 15.0 cm / s, not exceeding 14.0 cm / s, not exceeding 13.0 cm / s, not exceeding 12.0 cm / s, not exceeding 11.0 cm / s, not exceeding 10.0 cm / s, and any and all ranges and subranges therebetween.

[0133] Process parameters (e.g., precursor volume, gas flow rate, time interval, temperature, full (100%) or incomplete CVD yield, etc.) will typically depend on the equipment used, starting materials, desired product properties and / or other factors, and can be determined through routine experiments, modeling calculations, or prior experience.

[0134] In many cases, the CVD conditions employed are based on the Damcole number (defined as the dimensionless ratio of characteristic diffusion time to reaction time). A high Da number indicates a fast forward reaction, while a low Da number indicates a kinetically controlled reaction. In practice, the CVD processes described herein are performed at low Da numbers (e.g., <1, <0.5, <0.1). Within such a Da number range, the reaction rate is slow enough to allow the silicon-containing material (e.g., SiH4) to fully penetrate the carbon support and to uniformly deposit silicon throughout the pores of the carbon support. The characteristics of the Da number can be primarily controlled by the temperature selected for the CVD process, the choice of precursors, additive gases, and / or other factors.

[0135] In one implementation, the reactor and / or process employed provides uniformity in concentration and temperature for exposing the carbon black support to the silicon-containing gaseous precursor.

[0136] In a particular embodiment, the Si deposition within the carbon black support is characterized as “uniform,” meaning that the central portion of the carbon black support (e.g., with a particle size of approximately 10 micrometers) has the same or nearly the same silicon-to-carbon ratio as observed near the surface of the carbon black support. This can be measured by preparing a suitable cross-section of the silicon-carbon product and using that cross-section for time-of-flight secondary ion mass spectrometry, XPS, or other surface-sensitive techniques.

[0137] The processes described herein may include additional operations (steps) that may be performed after, during, or before CVD. For example, post-CVD steps may involve cooling and / or collecting silicon-carbon structures, size reduction (e.g., by milling), covering with a liquid such as pitch, spheroidization, or other product processing steps.

[0138] Other operations involve obtaining silicon-carbon composites of the desired average size. As mentioned above, the carbon black support can be or may be derived from CB pellets. Such pellets are commercially available or can be prepared using techniques known in the art, for example, high-purity CB (e.g., with a metal content of less than 10 ppm).

[0139] In some cases, the starting material is too large compared to the desired product particle size (e.g., about 10 micrometers in some cases). For example, the starting material may have an average size of about 100 micrometers to several thousand micrometers. In specific instances, the size of the starting material is in the range of less than 100 micrometers up to several millimeters, for example, about 0.1 mm to about 5 mm.

[0140] The relatively large starting particles and / or relatively large product structures obtained by permeating silicon into these large particles can be pulverized into the desired product size, such as an average size between 1 and 25 micrometers, through size reduction (e.g., grinding or milling operations). Equipment that can be used includes jet mills, ball mills, media mills, or other dry grinding equipment.

[0141] In one implementation, the size reduction step is performed prior to the CVD operation, and the smaller, broken particles are exposed to the Si-containing precursor.

[0142] In another implementation, grinding is performed after CVD. For example, the trade-off of fluidized beds is the potential loss of smaller particles entrained in the gas. This loss can be reduced by performing CVD with larger particles and then grinding the product particles after the silicon-carbon composite has been formed.

[0143] Size increases can also occur. For example, in a fluidized bed, porous carbon supports can be entrained in a flowing fluidizing gas and become "glued" together. These spontaneously formed aggregates are typically larger than the initial carbon support. For instance, a 10-micron porous carbon support can potentially form silicon-carbon aggregates as large as approximately 25, 50, 100 microns, or even larger. This size increase can be addressed through post-CVD size reduction operations. Malvern optics with flowing gas can be used to provide useful information and potential correlations.

[0144] Size reduction or size increase can also occur simultaneously with the exposure of porous carbon supports to Si precursors. For example, larger carbon entities can collide with each other, leading to size reduction. Smaller entities in a fluidized bed can spontaneously aggregate and form larger entities that can be held together by silicon deposition.

[0145] In some embodiments, graphitization is performed during a heat treatment step, which may be performed before and / or after the size reduction operation. In one embodiment, the starting material is already heat-treated graphitized CB material. In another embodiment, the heat treatment may be part of the process, wherein large particles are heat-treated prior to the size reduction step. In a further embodiment, the particles are jet-milled or pulverized prior to heat treatment and graphitization. A further embodiment uses untreated and ungraphitized CB.

[0146] Different approaches were used to prepare composites containing carbon black, and / or graphite, and silicon, and optionally CNTs, employing non-CVD technologies. Surprisingly and unexpectedly, composites prepared by mechanically combining the components using wet or dry mixing techniques were found to be more advantageous than those produced by CVD. In this approach, the Si entity can be mechanically incorporated into the carbonaceous scaffold without loss of electrode performance. In other words, composites prepared by CVD infiltration through mechanical component combination, independent of the silicon entity, performed as well as composites prepared by CVD technology.

[0147] In one example, the carbon in the carbon support comprises fine graphite particles or a combination of fine graphite particles with CB and / or CNTs. In another example, the carbon in the carbon support comprises CB, optionally combined with CNTs, and does not include graphite. In embodiments, the carbon support is prepared using a non-CVD technique with 0-100% CB, 0-100% graphite, and 0-25% CNTs. In some cases, a binder may be added.

[0148] Silicon can be derived from the grinding of metallurgical-grade silicon or from other sources.

[0149] A non-CVD method for preparing silicon-carbon composites relies on dry mixing. Suitable techniques that can be used or adapted include mechanical agitation, shaking, stirring, etc., and can rely on equipment such as jet mills, tube mills, acoustic mixers, extruders, planetary mixers, other mixing devices (e.g., laboratory-scale mixers), and equipment suitable for pilot-scale evaluation, full-scale industrial manufacturing, etc.

[0150] If more than two components are used, the mixing process can be carried out in one step, with all components added simultaneously or sequentially, where the additional components are combined with a pre-blended mixture of fewer components.

[0151] A step-by-step sequence can be achieved by using one type of equipment for the first operation (e.g., preparing a pre-blend) and another type of equipment for subsequent mixing operations. The same applies to shearing and / or other mixing parameters.

[0152] For illustration, separate powders of silicon and / or CB and / or graphite particles are mixed with optional CNTs in dry form with an optional binder, such as polyacrylic acid, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), other binders typically used for Li-ion battery cathodes or anodes, or any combination thereof.

[0153] Wet mixing alternatives involve forming a slurry composed of silicon nanoparticles and one or more carbon components (e.g., CB and / or graphite particles and optional CNTs), typically an aqueous slurry. The aqueous slurry may further include surfactants, wetting agents, rheology modifiers such as thickeners, defoamers, and / or other components. In some cases, the aqueous slurry will include one or more dispersants or binders, such as poly(vinylpyrrolidone), poly(vinylpyrrolidone-co-vinyl acetate), poly(vinyl butyral), poly(vinyl alcohol), poly(ethylene oxide), poly(propylene oxide), poly(propylene carbonate), cellulose-type dispersants such as methylcellulose, carboxymethylcellulose, ethylcellulose, hydroxymethylcellulose, and hydroxypropylcellulose; polyparboxylic acids such as poly(acrylic acid), polyacrylate, poly(methacrylate), poly(acrylamide), amide waxes, styrene-maleic anhydride resins, octylphenol ethoxylate, or other substances known in the art.

[0154] The slurry is thoroughly dispersed for spray drying and can be fed into a spray dryer, where a mechanical atomizer produces droplets. The droplets are then subjected to heated gas, typically followed by recovery of the spray-dried particles, which can be further processed as needed (e.g., sorting, classifying, grinding, etc.). Slurry characteristics and / or operating conditions can be determined through routine experiments, prior experience, etc.

[0155] Granulation systems represent another preparation route that does not require CVD. In this route, a binder is sprayed onto a powdered feed consisting of a combination of carbon components (e.g., CB and / or graphite fines and optional CNTs) and silicon nanoparticles, and the sprayed components are granulated into composite particles. Specific procedures and / or equipment that can be used include granulators originally developed for pharmaceutical, agricultural, and / or other industries.

[0156] Following mechanical mixing, further processing can be performed, including operations aimed at obtaining a desired composite particle size (e.g., between about 1 and about 25 micrometers, or about 10 micrometers in one instance). In some embodiments, the mixture containing CB and silicon is granulated and / or ground to the desired size and graded. For illustration, the silicon-carbon structure obtained by mechanical mixing can be granulated, dried, jet-milled, and / or graded to provide composite particles of about 10 micrometers.

[0157] In one embodiment, a solution of water, binder, and optionally dispersant is combined with a mixture of nano-silicon and carbon materials. This is then granulated in a drum granulator or pin granulator. Thermal processing removes moisture from the granules. The size of the dry granules can be modified as needed by jet milling or other techniques known in the art. Sorting and / or grading steps can be performed before and / or after jet milling.

[0158] The processes described herein may include one or more covering operations, wherein the silicon-carbon composite or structure is (partially or completely) covered by silicon and / or materials other than silicon.

[0159] As already noted, a key objective of the silicon-carbon composites described herein involves reducing or minimizing the formation of large surface area SEIs. Alternatives to or complementing the aforementioned carbon surface area considerations, available techniques involve maintaining a high surface area of ​​the carbon substrate (CB) and the silicon supported on the CB (thus protecting the interior of the silicon-carbon composite entity). In one approach, this is achieved by sealing or “closing” the pores at the surface, thereby blocking access to the inner surface regions of the carbon and silicon. The sealing or “closing” of pores can be accomplished by covering the silicon-carbon composite particles with one or more of silicon, low-valence silicon oxides, or carbon. As used herein, the term “closing” refers to a process in which the CVD operation continues until silicon or a material other than silicon (e.g., carbon) is deposited into the external (or surface) pores of the porous carbon support to block the pores and ultimately close or “close” them.

[0160] In addition to protecting the high surface area CB and silicon inside the composite and thus reducing any irreversible absorption of silicon and / or minimizing SEI formation, the blockage also prevents external reagents from reaching the interior of the product structure.

[0161] The conditions for closure can be determined through routine experiments, experience, modeling, or other techniques.

[0162] In one approach, silicon is deposited into the interior of a carbon support, and then the operation of the CVD system is shifted to a higher temperature and a correspondingly higher silicon deposition rate. This increases the Damcole number, for example, to greater than 1, greater than 5, or greater than 10. This, in turn, causes Si to preferentially deposit on the surface of the aggregates. An exemplary process is performed with a Damcole number less than 1 (unity) based on particle size, the silane diffusion coefficient in the gas phase, and the silane reaction rate; the CVD is continued long enough to close the pores on the surface of the porous carbon support by filling them with silicon.

[0163] Figure 7 The schematic diagram shows silicon-carbon composite particles (composed of porous carbon support 10 containing silicon entities 12, such as...) Figure 3 Silicon coating 14 on the surface (as shown).

[0164] In another embodiment, the silicon-carbon composite is coated with a material other than silicon, in one pathway being carbon. For example, Figure 8 It is carbon covering 16 in Figure 3 A schematic diagram of the surface of silicon-carbon composite particles.

[0165] Carbon-covered operations can be carried out via CVD using carbon-containing precursors such as methane, natural gas, propane, butane, acetylene, ethylene, propylene, benzene, other saturated, unsaturated or aromatic hydrocarbons, or mixtures thereof.

[0166] In some embodiments, the silicon-carbon composite may be coated with both silicon and a material other than silicon (e.g., carbon). The sealing process can be performed sequentially. For example, silicon can be used to close the pores, followed by covering the entire structure with carbon. A schematic diagram of the resulting silicon-carbon composite particles, first covered with a silicon layer 14 and then with a carbon layer 16, is shown below. Figure 9 middle.

[0167] In some embodiments, when the silicon-carbon composite includes graphite, such as Figure 10 The schematic diagram of the silicon-carbon composite particle 10 shown includes graphite particles 12 (which may be fine graphite particles), carbon black particles 14, carbon nanotubes 16, silicon nanoparticles 18, and a covering 20. The covering 20 seals (closes) the surface pores, thereby protecting the interior 22 of the silicon-carbon composite particle 10 from contact with the battery electrolyte.

[0168] Conveniently, the carbon covering operation can be carried out in the same reactor used to introduce silicon into the porous carbon support, optionally followed by silicon sealing. Typically, this is accomplished by switching the feed gas (e.g., from silane to propane) and changing the temperature.

[0169] In one approach, relatively large particles are milled to form the porous carbon support described herein. Silicon is then deposited by CVD, for example, to achieve a 50% loading, optionally followed by silicon sealing, and then carbon covering (e.g., via CVD using a C-containing precursor) to form a partially or completely covered silicon-carbon structure.

[0170] In different approaches, relatively large particles are first exposed to a Si-containing precursor during a CVD operation, then the size of the silicon-carbon material is reduced, for example by grinding, to obtain silicon-carbon structures of the desired size (e.g., 10 micrometers). These are then covered with a carbon layer (e.g., by using CVD with a C-containing precursor) to form partially or completely covered silicon-carbon structures. In one implementation, this approach involves transferring the material to a size-reduction device, such as a jet mill. Once pulverized, the material can be returned to the CVD reactor for carbon covering.

[0171] In many cases, the thickness of the capping produced by silicon and / or carbon capping operations will depend on the surface porosity. In many cases, the pore size at the surface of the porous carbon support is approximately 10–100 nm. To seal these surface pores, it may be necessary to deposit a capping material with a thickness greater than approximately 5–50 nm.

[0172] The sealing process can produce a coating or layer that covers 100% or nearly 100% of the silicon-carbon composite structure. It is also possible to prepare particles that are only partially (e.g., 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, 10% or less) covered with silicon and / or carbon.

[0173] Techniques that can be used to assess the properties of coverings include, but are not limited to, BET surface area, cross-sectional microscopy, and elemental surface composition analysis, such as by SIMS, Auger, or XPS. Completely covered particles will block access to the high surface area within the solid, resulting in a low measurable surface area. Cross-sectional microscopy will show a continuous layer at the surface of a silicon-carbon solid. SIMS, Auger, and XPS will only show the presence of silicon, for example, if the pores are closed by silicon.

[0174] In certain embodiments, a non-CVD technique is used to coat a silicon-carbon composite structure with a carbon layer. For example, the carbon coating can be formed by decomposing a solid carbon-containing precursor that has been applied to the surface of composite particles, which include silicon, CB, and optionally CNTs. Illustrative embodiments utilize materials typically having a high carbon content, such as sugar, bitumen, sol-gel, or tar.

[0175] In one approach, silicon-containing complex particles are mixed with an aqueous solution of sugars (e.g., glucose, sucrose, fructose, other polysaccharides, or combinations of different sugar types).

[0176] As is known in the art, simple direct mixing, spraying, dip coating, granulator coating, or other suitable techniques can be used. The coated granules can be dried to remove water, leaving a thin layer of sugar on their surface. The sugar-coated granules are then heated in an inert atmosphere (e.g., nitrogen, argon, etc.) at a temperature typically ranging from 400°C to 800°C. The pyrolysis process takes place in an anaerobic environment and involves the decomposition of carbon-rich sugars, which break down to form carbon, typically in the thin layer covering the substrate granules. The structure, porosity, and / or other properties of the carbon layer can be controlled by varying the pyrolysis conditions, including temperature, heating rate, duration, and / or other process parameters.

[0177] Another approach involves bitumen (a complex mixture that can be derived from petroleum, coal tar, or synthetic sources of polycyclic aromatic hydrocarbons (PAHs)). Its high carbon content and thermoplastic behavior make bitumen an excellent precursor for carbon coatings, offering good control over the properties of the final carbon layer, such as the degree of graphitization, porosity, and electrical conductivity.

[0178] Asphalt is typically applied to substrate particles in a molten state or as a solution in a suitable solvent. In many cases, the substrate particles are uniformly coated with asphalt. If the asphalt is applied in solution form, the solvent evaporates, leaving a uniform asphalt coating on the particles. The asphalt-coated particles are then heated in an inert atmosphere (e.g., nitrogen or argon) to a temperature typically between 600°C and 1000°C. In this process, known as “carbonization,” the asphalt is broken down into carbonaceous material. The temperature required to convert the asphalt into carbon for coating purposes will typically depend on the type of asphalt used, the desired properties of the carbon layer, and / or other factors.

[0179] More specifically, different asphalts (petroleum asphalt, coal tar pitch, or other types of asphalt) have different compositions and therefore different thermal behaviors. However, there are general temperature ranges that can be considered effective for the conversion process. The pyrolysis of asphalt typically begins at temperatures between about 350°C and 400°C. This initial stage involves the evolution of volatile compounds and the formation of more cross-linked structures. As the temperature increases (typically between about 400°C and 500°C), the asphalt begins to transform into the mesophase asphalt. This mesophase is an important intermediate stage in which the asphalt begins to form a more ordered graphite structure. Complete carbonization of asphalt usually occurs at higher temperatures, typically in the range of about 600°C to about 1000°C. During complete carbonization, the asphalt completely loses its volatile components and forms a stable carbon structure, becoming a solid carbon material.

[0180] In some embodiments, the solid carbon-containing precursor (e.g., bitumen) may contain carbon particles, such as carbon black, carbon nanotubes, carbon nanostructures, and combinations thereof. The carbon particles may be mixed in at 5%, 10 wt%, and up to 20 wt%. The carbon particles can improve conductivity and adhesion to other particles. The carbon particles can also help block surface pores on the composite particles.

[0181] In LIB applications, the silicon-carbon material described herein may represent the entire anode material or a portion thereof. In one embodiment, the silicon-carbon composite is used as an anode additive.

[0182] In anode applications, silicon-carbon composites can be provided in combination with electroactive materials (also referred to herein as “active electrode materials” or simply “active materials” or “AM”), such as graphite, including natural graphite, artificial graphite (e.g., bulk artificial graphite (MAG)), or blends of both. Mesocarbon microspheres (MCMB), mesophase pitch-based carbon fibers (MCF), and vapor-grown carbon fibers (VGCF) can also be used. Silicon-carbon composites can also be added to, for example, materials containing silicon, silicon-graphite composites, or nano-silicon (Si) or SiO₂. x In active materials of particulate graphite.

[0183] For illustration, the graphite anode may employ a silicon-carbon composite as described herein, in an amount of about 1 wt% to about 20 wt%, for example, about 1 to about 5, about 10, about 15, about 20 wt%; or about 5 to about 10, about 15, about 20 wt%; or about 10 to about 15, about 20 wt% or about 15 to about 20 wt%.

[0184] In practice, the ratio of silicon-carbon composite to graphite is 1:100, 1:50, 1:20, 1:10, 1:5, or 1:1.

[0185] The principles described herein can also be used with other active anode materials, such as those known or currently explored, or those to be developed in the future. Examples include, but are not limited to: (a) intercalation / deintercalation materials (e.g., carbon-based materials, porous carbon, graphene, TiO2, Li4Ti5O). 12 (e) Alloy / dealloy materials (e.g., Si, SiO2) x (c) Doped Si, Ge, Sn, Al, Bi, SnO2, etc.; and (d) Conversion materials (e.g., transition metal oxides (MnO2)). x O y NiO, Fe x O y CuO, Cu2O, MoO2, etc.), derived from formula M x X y The terms represent metal sulfides, metal phosphides, and metal nitrides, where X = S, P, N. Some examples use alloys of silicon or germanium.

[0186] In another embodiment, the entire anode is made of a silicon-carbon composite material, thus eliminating the need for a separate electroactive material, such as graphite.

[0187] It has been unexpectedly found that the ratio of OAN (oil adsorption value) to BET (Brunauer-Emmett-Teller surface area) of carbon black carriers is in the range of 1 to 10, wherein OAN is measured by ASTM D2414-23A and reported in ml / 100g carbon, and BET is measured by ASTM D6556-21, and / or (ii) the mass of silicon per 100g carbon black carrier in g is less than or equal to 0.75. Silicon-carbon composites of OAN offer advantages for use in anode compositions, such as those for lithium-ion batteries. In some embodiments, the OAN:BET ratio of the carbon black support can be in the range of 1 to 10, 1 to 9, 1 to 8, 1 to 7, 1 to 6, 5, 2 to 10, 2 to 9, 2 to 8, 2 to 7, 2 to 6, 3 to 10, 3 to 9, 3 to 8, 3 to 7, 3 to 6, 4 to 10, 4 to 9, 4 to 8, 4 to 7, 5 to 10, 5 to 9, 5 to 8, 5 to 7, 6 to 10, 6 to 9, 6 to 8, 7 to 10, 7 to 9, 8 to 10, or any and all ranges and subranges thereof. Balancing the OAN to BET ratio minimizes the formation of a solid electrolyte interface (SEI) caused by the contact between the electrolyte and the carbon black support, which is important because the SEI reduces the amount of lithium in the LIB and thus reduces energy capacity. Therefore, minimizing SEI formation can lead to an improved energy capacity of the LIB. In some embodiments, the mass of silicon per 100g of carbon black carrier, expressed in grams, may be within the range of: less than or equal to 0.75. OAN is greater than or equal to 0.5 OAN, less than or equal to 0.75 OAN is greater than or equal to 0.55 OAN, less than or equal to 0.75 OAN is greater than or equal to 0.6 OAN, less than or equal to 0.75 OAN is greater than or equal to 0.65 OAN, less than or equal to 0.7 OAN is greater than or equal to 0.5 OAN, less than or equal to 0.7 OAN is greater than or equal to 0.55 OAN, less than or equal to 0.7 OAN is greater than or equal to 0.6 OAN, less than or equal to 0.7 OAN is greater than or equal to 0.65 OAN, less than or equal to 0.65 OAN is greater than or equal to 0.5 OAN, less than or equal to 0.65 OAN is greater than or equal to 0.55 OAN, less than or equal to 0.65 OAN is greater than or equal to 0.6 OAN, less than or equal to 0.6 OAN is greater than or equal to 0.5 OAN, or any and all ranges and subranges thereof. Balancing OAN (which can be related to the void volume in the carbon black support) with the amount of silicon in the pores (in order to allow room for the volume expansion of silicon without leaving too much space and reducing energy density) is beneficial for improved energy density for LIB.

[0188] Therefore, silicon-carbon composites can typically be provided in the anode at any suitable amount, depending on factors such as the specific application, the anode active material used (if any), the manufacturing process, and the presence of other components, to name a few. In practice, silicon-carbon composites are provided in amounts between about 20 and about 100 wt%. In some cases, silicon-carbon composites in the range of 20-50% may be preferred over composites with higher loadings.

[0189] In addition to the silicon-carbon composite and the anode active material (if graphite is used), the anode composition may further include other components, such as conductive additives, such as conductive carbon additives (CCA), binders, plasticizers, and / or other components. In many cases, the binder is provided in relatively small amounts (small amounts, e.g., 2 to 3 wt% or 0.1 to 5 wt%). For anode applications, the silicon-carbon composite particles disclosed herein are particularly compatible with binders for anodes that consist of, are substantially composed of, or contain lithium-ion polyacrylic acid (LiPAA). Other binders may be used.

[0190] CCA is often supplied in amounts of 1 wt% or less. Examples of CCA include CB (which may be the same as or different from the CB in the silicon-carbon composite) and / or carbon nanotubes (CNTs). One implementation uses single-walled carbon nanotubes (SWCNTs), which can maintain good electrical contact with graphite and the silicon-carbon composite as scale changes during anodic operation.

[0191] Illustrative anode compositions include graphite, silicon-carbon composites as described herein, LiPAA binders, and SWCNTs.

[0192] Silicon-carbon composites can be combined with anode active materials (e.g., graphite) using techniques known in the art or developed in the future. The resulting compositions, in the form of slurries, pastes, pourable granular materials, etc., can be used to manufacture LIB anodes.

[0193] The LIBs described herein further include cathodes such as LCO (lithium cobalt oxide), LMO (lithium manganese oxide), NCM (lithium nickel cobalt manganese oxide), NCA (lithium nickel cobalt aluminum oxide), LCP (lithium cobalt phosphate), LFP (lithium iron phosphate), LMFP (lithium manganese iron phosphate), LFSF (lithium iron fluorosulfate), and LTS (lithium titanium sulfide) cathodes. Materials such as these are generally referred to herein as “lithium transition metal compounds,” such as “lithium transition metal oxides.” In addition to cathode materials based on intercalation chemistry (e.g., chemical reactions typically involving the transfer of a single electron), other types of cathode materials (e.g., those with lithium ions intercalated in FeF3) can transfer multiple electrons through more complex reaction mechanisms (called conversion reactions). Other active cathode materials known in the art or developed in the future may be used.

[0194] Some implementations utilize NCM (also known as "NMC") or NCA cathode compositions. These materials are generally known to those skilled in the art. In addition, many battery formulations in powder form (e.g., NCM 622) are commercially available.

[0195] More specifically, NCM can be derived from formula Li 1+x (Ni y Co 1-y-z Mn z ) 1-x O2 represents a value where x is in the range of 0 to 1, y is in the range of 0 to 1 (e.g., 0.3–0.8), and z is in the range of 0 to 1 (e.g., 0.1–0.3). Examples of NCM include Li. 1+x (Ni 0.33 Co 0.33 Mn 0.33 ) 1-x O2, Li 1+x (Ni 0.4 Co 0.3 Mn 0.3 ) 1-x O2, Li 1+x (Ni 0.4 Co 0.2 Mn 0.4 ) 1-x O2, Li 1+x (Ni 0.4 Co 0.1 Mn 0.5 ) 1-x O2, Li 1+x (Ni 0.5 Co 0.1 Mn 0.4 ) 1-x O2, Li 1+x (Ni0.5 Co 0.3 Mn 0.2 ) 1-x O2, Li 1+x (Ni 0.5 Co 0.2 Mn 0.3 ) 1-x O2, Li 1+x (Ni 0.6 Co 0.2 Mn 0.2 ) 1-x O2, Li 1+x (Ni 0.8 Co 0.1 Mn 0.1 ) 1-x O2 and Li 1+x (Ni 0.9 C 0.05 Mn 0.05 ) 1-x O2.

[0196] NCA can be derived from formula Li 1+x (Ni y Co 1-y-z Al z ) 1-x O2 represents a value where x is in the range of 0 to 1, y is in the range of 0 to 1, and z is in the range of 0 to 1. An example of NCA is Li. 1+x (Ni 0.8 Co 0.15 Al 0.05 ) 1-x O2.

[0197] In addition to the two electrodes, a typical LIB contains a suitable electrolyte. Examples include, for instance, ethylene carbonate-dimethyl carbonate-ethyl methyl carbonate (EC-DMC-EMC), vinylene carbonate (VC), LiPF6; ethylene carbonate-diethyl carbonate (EC-DEC, LiPF6; or (EC-DMC), LiPF6). Furthermore, the electrolyte composition may contain known SiO2 enhancements. x Special additives that enhance the performance of silicon-containing anodes, such as fluorinated carbonates like fluoroethylene carbonate, can be used. In the laboratory, a suitable separator (e.g., Whatman GF / A) can be used to absorb electrolytes and prevent electrical contact between electrodes while allowing Li ion diffusion. In some cases, membrane separators made of polypropylene / polyethylene (e.g., Celgard 2300) can also be used.

[0198] An anode containing the silicon-carbon structure described herein can be incorporated into a lithium-ion battery according to methods known in the art, such as those described in Yuping Wu's "Lithium Ion Batteries Fundamentals and Applications," CRC Press, (2015). In practice, the battery is a coin cell, such as a 2032 coin cell, an 18650 cylindrical cell, a pouch cell, etc.

[0199] The principles described herein can be used and / or applied to the manufacture of other energy storage devices, such as primary alkaline batteries, primary lithium batteries, nickel-metal hydride batteries, sodium batteries, lithium-sulfur batteries, lithium-air batteries, and supercapacitors. Methods for manufacturing such devices are known in the art and are described, for example, in TR Crompton's "Battery Reference Book," Newness (2000).

[0200] Electrodes and / or batteries containing silicon-carbon composites can be characterized using a variety of techniques. Examples include, but are not limited to, electron microscopy, such as TEM, SEM, X-ray tomography, Raman spectroscopy, and other suitable qualitative or quantitative analytical methods. Anode performance can be tested using procedures known in the art or applicable or developed techniques. Suitable methods include, for example, in-plane and through-plane electrode conductivity, electrochemical impedance spectroscopy (EIS), constant current charge-discharge, hybrid pulsed power capacity (HPPC), and cycling. Mechanical evaluation techniques include peel tests (e.g., 90°, 180°, T-peel, various clamps), tensile tests, and bending tests (mandrel experiments), to name just a few.

[0201] The present disclosure is further illustrated by the following non-limiting examples.

[0202] illustration

[0203] Example 1

[0204] Samples were prepared by static bed reactor CVD using the Easy Tube® 3000 system from a CVD equipment provider. A thin layer of LITX® HP (Cabot Corporation) was placed on a quartz tray, which was then placed in the reactor. The reactor was evacuated to a low pressure and purged with argon, then heated to the specified temperature. Once the reactor was at the specified temperature, silane (a silicon-containing precursor) was allowed to flow through the reactor at a set rate for a set time to allow silicon to deposit on the LITX® HP layer and form a silicon-carbon composite. The process parameters are summarized in Table A below. For some of the samples below, a carbon coating was applied by increasing the reactor temperature and pressure and allowing ethylene (a carbon-containing precursor) to flow at a set rate for a set time.

[0205] Table A

[0206]

[0207] Materials were characterized by thermogravimetric analysis (TGA), surface area (BET), and scanning electron microscopy (SEM).

[0208] Thermogravimetric analysis was performed in air on a TA Instrument Q600 horizontal TGA / DSC. The temperature was increased at 10°C / min up to 650°C, then held for at least two hours to allow all carbon to burn off, followed by an increase at 10°C / min up to 1300°C. At 1300°C, no further weight change was observed, indicating that all silicon was completely oxidized to SiO2. The weight of silicon dioxide can be used to determine the total Si wt% using the following equation:

[0209]

[0210] The value is reported as the average of three replicates.

[0211] The sample was examined using a ZEISS Ultra Plus field emission scanning electron microscope equipped with an Oxford AZtec X-ray spectroscopy system, employing both scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM / EDS). All images were acquired using a split detector mode. The left side of the image was acquired using an energy-selective backscattering detector, and the right side was collected using an InLens secondary electron detector. Backscattered electron images were formed by collecting reflected electrons emitted by the elastic scattering of the electron beam. These images can reveal compositional differences in the sample; heavier elements (in this case, silicon) will appear brighter than lighter elements. Particles were sprinkled onto carbon ribbons for imaging.

[0212] Surface area was measured by BET on a Micromeritics TriStar 3030 Plus. Samples were degassed at 200°C for 60 min under a nitrogen flow; measurements were taken using partial pressures ranging from 0.05 to 0.5 P / P0; and analysis was performed using BET theory. Results are summarized in Table B below, where controls were not exposed to silane.

[0213] The OAN of the carbon support was measured by ASTM D2414-23A and was 231.7 ml / 100 g carbon for all samples. Therefore, 0.75 The OAN value is 173.8, and as can be seen in the table below, all carbon supports have a value less than 0.75. The silicon mass per 100g of OAN carbon black carrier. The BET surface area of ​​the carbon carrier was measured by ASTM D6556-21 and was 89.1m² for all samples. 2 / g. The OAN / BET of the sample is 2.60.

[0214] Table B

[0215]

[0216] Example 2

[0217] Using the formulation in Table C below, button cell batteries were prepared using a 3-step mixing process with a Thinky ARE-310 mixer. The Li-PAA binder was prepared by dissolving polyacrylic acid (MW: 450k, Sigma Aldrich) in water and adjusting the pH to 7 with LiOH. Tuball SWCNT and Li-PAA were mixed at 2000 rpm for 10 minutes. Water and the silicon-carbon composite were added and mixed at 2000 rpm for 5 minutes. Graphite was added and the composition was mixed for 20 minutes, with a settling step to prevent the paste from overheating.

[0218] Table C

[0219]

[0220] The slurry was applied to a 9μm copper foil at a thickness of 150 micrometers using a doctor blade coater, then dried and calendered to a thickness of 1.3 g / cm. 3The density was then determined. The coated sheet was then stamped into 15 mm discs. 2032 half-cell button cells were assembled in an argon-filled glove box using lithium chips, Whatman GF / A glass fiber separators, 1 mm thick spacers, and 175 μL of 1.0 M LiPF6 + 10% fluoroethylene carbonate in ethylene carbonate / dimethyl carbonate / diethyl carbonate (1:1:1 volume) as the electrolyte. The half-cell cells were tested at 25 °C on a Maccor tester, with one formation cycle at C / 20, a second formation cycle at C / 10, and then cycling at C / 3. The results are shown in Table D below and indicate that the silicon-carbon composite significantly increased the initial capacity compared to the control, and that the cycling performance of the silicon-carbon composite was comparable to or better than the control. Furthermore, if a silicon-carbon composite with a carbon coating is to be prepared for manufacturing a half-cell battery as described above, it is expected that the carbon coating will slightly reduce the initial capacity due to the added carbon, but it will result in a higher first-cycle efficiency and better capacity retention compared to a half-cell battery with an uncovered silicon-carbon composite. In this case, the carbon coating is prepared by dissolving 10 mg of coal tar pitch in 20 ml of tetrahydrofuran and then adding 50 mg of the silicon-carbon composite. It is vigorously mixed, then evaporated, and the silicon-carbon composite residue covering the pitch is collected. In a furnace, the composite is heated to 240°C at 5°C / min in air and then soaked for 3 hours. It is then heated at 1000°C for 1 hour under argon to carbonize the coating.

[0221] Table D

[0222]

[0223] Example 3

[0224] The performance of button cell batteries prepared using a silicon-carbon composite prepared by mechanical mixing (sample 9), a silicon-carbon composite prepared by silicon CVD (sample 1 described in Example 1 above), and a control without silicon (the control described in Example 1 above) were compared.

[0225] The coin cell battery was prepared using the same process as in Example 2, and the formulation, by weight percentage on a dry basis, is listed in Table E below. In the manufacture of Sample 9, the silicon-carbon composite was a blend of 13.1 wt% silicon (silicon nanoparticles (US Research Nanomaterials Inc.)) and 30.8 wt% carbon black support (conductive carbon black particles (LITX® HP, Cabot Corporation)). The OAN of the carbon support in Sample 9 was measured by ASTM D2414-23A and was 231.7 ml / 100 g carbon. The silicon mass per 100 g of carbon in the carbon black support was 30 g. Therefore, 0.75 The OAN value is 173.8, and therefore the carbon support has a value less than 0.75. OAN silicon mass / 100g carbon black carrier. The BET surface area of ​​the carbon carrier in sample 9 was measured by ASTM D6556-21 and was 89.1 m². 2 / g. The OAN / BET of the carbon black carrier in sample 9 is 2.60.

[0226] Table E

[0227]

[0228] Half-cell battery performance summary Figure 11 The graph shows the relationship between the discharge capacity (mAh / g) and cycle behavior of the half-cell batteries for the control (dashed line), sample 1 (dotted line), and sample 9 (solid line).

[0229] The cell performance of the CB-silicon mechanical mixture, Sample 9, is within the error range of the example (Sample 1) where silicon is deposited onto a carbon support by CVD. Both show a significant improvement in capacity compared to the control sample (control) prepared without silicon.

[0230] aspect

[0231] Aspect 1. Silicon-carbon composite, comprising:

[0232] Carbon black carrier; and

[0233] Silicon located in the pores of the carbon black carrier, wherein:

[0234] The ratio of OAN (oil adsorption value) to BET (Brunauer-Emmett-Teller surface area) of the carbon black carrier is in the range of 1 to 10, wherein OAN is measured by ASTM D2414-23A and reported in ml / 100g carbon, and BET is measured by ASTM D6556-21.

[0235] The mass of silicon per 100g of carbon black carrier, expressed in grams, is less than or equal to 0.75. OAN.

[0236] Aspect 2. The silicon-carbon composite according to aspect 1, wherein the silicon-carbon composite has a D50 volumetric particle size in the range of 5 to 25 micrometers.

[0237] Aspect 3. The silicon-carbon composite according to aspect 1 or 2, wherein the silicon-carbon composite further comprises a coating of silicon, carbon, or a combination thereof.

[0238] Aspect 4. The silicon-carbon composite according to any one of the preceding aspects, wherein the pores of the carbon black carrier are closed.

[0239] Aspect 5. The silicon-carbon composite according to any one of the preceding aspects, wherein the carbon black carrier has a density of less than or equal to 42. L c Grain size.

[0240] Aspect 6. The silicon-carbon composite according to any one of the preceding aspects, wherein the carbon black carrier contains less than 100 ppm of metallic impurities.

[0241] Aspect 7. The silicon-carbon composite according to any one of the preceding aspects, wherein the carbon black carrier has an OAN in the range of 32 to 400 ml / 100 g carbon.

[0242] Aspect 8. The silicon-carbon composite according to any one of the preceding aspects, wherein the carbon black support has a thickness of 3.2 to 400 μm. 2 BET within the range of / g.

[0243] Aspect 9. The silicon-carbon composite according to any one of the preceding aspects, further comprising graphite.

[0244] Aspect 10. The silicon-carbon composite according to aspect 9, wherein the graphite comprises graphite particles having a particle size of not more than 1 micrometer.

[0245] Aspect 11. The silicon-carbon composite according to any one of the preceding aspects, wherein the carbon black support is an aggregate of carbon black aggregates.

[0246] Aspect 12. The silicon-carbon composite according to any one of the preceding aspects, wherein the silicon comprises silicon nanoparticles.

[0247] Aspect 13. The silicon-carbon composite according to any one of the preceding aspects, wherein the silicon in the pores of the carbon black support is in the form of unconnected silicon entities.

[0248] Aspect 14. The silicon-carbon composite according to any one of Aspects 1-13, wherein the silicon in the pores of the carbon black support has the form of silicon entities, and at least some of the silicon entities are interconnected.

[0249] Aspect 15. An anode composition comprising:

[0250] The silicon-carbon composite according to any one of the foregoing aspects is used as the anode active material.

[0251] Aspect 16. The anode composition according to aspect 15 further comprises additional anode active material.

[0252] Aspect 17. The anode composition according to aspect 16, wherein the anode active material is graphite.

[0253] Aspect 18. The anode composition according to any one of aspects 15-17 further comprises carbon nanotubes.

[0254] Aspect 19. A lithium-ion battery comprising an anode composition according to any one of Aspects 15-18.

[0255] Aspect 20. A method for preparing a silicon-carbon composite, the method comprising:

[0256] The carbon black support is exposed to the precursor at a temperature sufficient to decompose the silicon-containing precursor and deposit silicon within the pores of the carbon black support to produce a silicon-carbon composite, wherein:

[0257] The ratio of OAN (oil adsorption value) to BET (Brunauer-Emmett-Teller surface area) of the carbon black carrier is in the range of 1 to 10, wherein OAN is measured by ASTM D2414-23A and BET is measured by ASTM D6556-21.

[0258] The silicon mass per 100g of carbon black carrier is less than or equal to 0.75%. OAN.

[0259] Aspect 21. The method according to aspect 20 further includes fluidizing the carbon black at a minimum fluidization rate of at least 0.1 cm / s while exposing the carbon black support to the silicon-containing precursor.

[0260] Aspect 22. The method according to aspect 20, wherein the method is carried out in a fluidized bed, moving bed, fixed bed, stirred bed or rotary tube furnace.

[0261] Aspect 23. The method according to any one of Aspects 20-22, wherein the method is carried out in an apparatus that provides uniform concentration and temperature conditions.

[0262] Aspect 24. The method according to any one of Aspects 20-23, wherein the method is carried out with a Damköhler number less than 1 based on particle size, precursor diffusion coefficient in the gas phase, and precursor reaction rate.

[0263] Aspect 25. A method for preparing a silicon-carbon composite, the method comprising:

[0264] Carbon black carriers are mechanically combined with silicon nanoparticles to form silicon-carbon composites, wherein:

[0265] The ratio of OAN (oil adsorption value) to BET (Brunauer-Emmett-Teller surface area) of the carbon black carrier is in the range of 1 to 10, wherein OAN is measured by ASTM D2414-23A and BET is measured by ASTM D6556-21.

[0266] The silicon mass per 100g of carbon black carrier is less than or equal to 0.75%. OAN.

[0267] Aspect 26. The method according to aspect 25 further includes mechanically combining carbon nanotubes with the carbon black carrier and silicon nanoparticles.

[0268] Aspect 27. The method according to aspect 25 or 26 further includes mechanically combining the adhesive with the carbon black carrier and silicon nanoparticles.

[0269] Aspect 28. The method according to any one of Aspects 25-27, wherein the mechanical combination comprises dry mixing of powders, wet mixing in a slurry, or granulation of powders sprayed with powder.

[0270] Aspect 29. The method according to any one of Aspects 20-28, wherein the silicon-carbon composite has a D50 volumetric particle size in the range of 5 to 25 micrometers.

[0271] Aspect 30. The method according to any one of Aspects 20-29, wherein the carbon black carrier has a density of less than or equal to 42. L c Grain size.

[0272] Aspect 31. The method according to any one of Aspects 20-30, wherein the carbon black carrier contains less than 100 ppm of metallic impurities.

[0273] Aspect 32. The method according to any one of Aspects 20-31, wherein the carbon black carrier has an OAN in the range of 32 to 400 ml / 100 g carbon.

[0274] Aspect 33. The method according to any one of Aspects 20-32, wherein the carbon black carrier has a thickness of 3.2 to 400 μm. 2 BET within the range of / g.

[0275] Aspect 34. The method according to any one of aspects 20-33 further includes adding graphite to the silicon-carbon composite.

[0276] Aspect 35. The method according to aspect 34, wherein the graphite comprises graphite particles with a particle size of not more than 1 micrometer.

[0277] Aspect 36. The method according to any one of Aspects 20-35, wherein the carbon black carrier is prepared from carbon black granules.

[0278] Aspect 37. The method according to any one of Aspects 20-36, wherein the carbon black is graphitized.

[0279] Aspect 38. The method according to any one of Aspects 20-36, wherein the carbon black is not graphitized.

[0280] Aspect 39. The method according to any one of Aspects 20-38, wherein the carbon black carrier is an aggregate of carbon black aggregates.

[0281] Aspect 40. The method according to any one of Aspects 20-39, wherein the silicon in the pores of the silicon-carbon support has the form of discrete, unconnected silicon entities.

[0282] Aspect 41. The method according to any one of Aspects 20-39, wherein the silicon in the pores of the silicon-carbon support has the form of silicon entities, at least some of which are interconnected.

[0283] Aspect 42. The method according to any one of Aspects 20-41, wherein the silicon deposited within the pores of the carbon black carrier is in the form of silicon nanoparticles.

[0284] Aspect 43. The method according to any one of Aspects 20-42, wherein the mass ratio of silicon to carbon in the silicon-carbon composite is between 20:80 and 80:20.

[0285] Aspect 44. The method according to any one of Aspects 20-43 further includes sealing the pores of the silicon-carbon composite.

[0286] Aspect 45. The method according to any one of Aspects 20-44, further comprising covering the silicon-carbon composite with silicon, carbon, or a combination thereof.

[0287] Aspect 46. The method according to aspect 45, wherein the silicon-carbon composite is covered by chemical vapor deposition.

[0288] Aspect 47. The method according to aspect 45, wherein the silicon-carbon composite is coated with carbon by thermal decomposition of a carbon-containing precursor at the surface of the silicon-carbon composite.

[0289] Aspect 48. The method according to aspect 45, wherein the carbon-containing precursor is sugar, pitch, tar, or sol-gel.

[0290] Aspect 49. The method according to aspect 45 further includes sealing the surface pores of the silicon-carbon composite with silicon, followed by carbon coating.

[0291] Aspect 50. The method according to any one of Aspects 20-49 further includes reducing the particle size of the carbon support or the silicon-carbon composite.

[0292] Aspect 51. The method according to any one of Aspects 20-50, further comprising combining the silicon-carbon composite with a LIB anode active material.

[0293] Aspect 52. The method according to any one of Aspects 20-51 further comprises preparing a LIB anode comprising the silicon-carbon composite.

[0294] Aspect 53. A method for preparing a silicon-carbon composite, the method comprising:

[0295] Graphite particles with a particle size of no more than 1 micrometer are mechanically combined with silicon nanoparticles to form silicon-carbon structures.

[0296] Aspect 54. The method according to aspect 53 further includes covering the silicon-carbon composite with a carbon layer to produce a covered silicon-carbon composite.

[0297] Aspect 55. Silicon-carbon composites prepared according to the methods of aspect 53 or 54.

[0298] While this disclosure has been specifically shown and described with reference to its preferred embodiments, those skilled in the art will understand that various changes in form and detail may be made therein without departing from the scope of this disclosure as covered by the appended claims.

Claims

1. A silicon-carbon composite, comprising: Carbon black carrier; and Silicon located in the pores of the carbon black carrier, wherein: The ratio of OAN (oil adsorption value) to BET (Brunauer-Emmett-Teller surface area) of the carbon black carrier is in the range of 1 to 10, wherein OAN is measured by ASTM D2414-23A and reported in ml / 100g carbon, and BET is measured by ASTM D6556-21. The mass of silicon per 100g of carbon black carrier, expressed in grams, is less than or equal to 0.

75. OAN.

2. The silicon-carbon composite of claim 1, wherein the silicon-carbon composite has a D50 volumetric particle size in the range of 5 to 25 micrometers.

3. The silicon-carbon composite according to claim 1 or 2, wherein the silicon-carbon composite further comprises a coating of silicon, carbon, or a combination thereof.

4. The silicon-carbon composite according to any one of the preceding claims, wherein the pores of the carbon black carrier are sealed.

5. The silicon-carbon composite according to any one of the preceding claims, wherein the carbon black carrier has a density of less than or equal to 42. L c Grain size.

6. The silicon-carbon composite according to any one of the preceding claims, wherein the carbon black carrier contains less than 100 ppm of metallic impurities.

7. The silicon-carbon composite according to any one of the preceding claims, wherein the carbon black carrier has an OAN in the range of 32 to 400 ml / 100 g carbon.

8. The silicon-carbon composite according to any one of the preceding claims, wherein the carbon black support has a particle size of 3.2 to 400 μm. 2 BET within the range of / g.

9. The silicon-carbon composite according to any one of the preceding claims, further comprising graphite.

10. The silicon-carbon composite of claim 9, wherein the graphite comprises graphite particles having a particle size of not more than 1 micrometer.

11. The silicon-carbon composite according to any one of the preceding claims, wherein the carbon black carrier is an aggregate of carbon black aggregates.

12. The silicon-carbon composite according to any one of the preceding claims, wherein the silicon comprises silicon nanoparticles.

13. The silicon-carbon composite according to any one of the preceding claims, wherein the silicon in the pores of the carbon black support is in the form of unconnected silicon entities.

14. The silicon-carbon composite according to any one of claims 1-13, wherein the silicon in the pores of the carbon black support is in the form of silicon entities, and at least some of the silicon entities are interconnected.

15. An anode composition comprising: The silicon-carbon composite according to any one of the preceding claims is used as the anode active material.

16. The anode composition according to claim 15, further comprising additional anode active material.

17. The anode composition according to claim 16, wherein the anode active material is graphite.

18. The anode composition according to any one of claims 15-17, further comprising carbon nanotubes.

19. A lithium-ion battery comprising the anode composition according to any one of claims 15-18.

20. A method for preparing a silicon-carbon composite, the method comprising: The carbon black support is exposed to the precursor at a temperature sufficient to decompose the silicon-containing precursor and deposit silicon within the pores of the carbon black support to produce a silicon-carbon composite, wherein: The ratio of OAN (oil adsorption value) to BET (Brunauer-Emmett-Teller surface area) of the carbon black carrier is in the range of 1 to 10, wherein OAN is measured by ASTM D2414-23A and BET is measured by ASTM D6556-21. The silicon mass per 100g of carbon black carrier is less than or equal to 0.75%. OAN.

21. The method of claim 20, further comprising fluidizing the carbon black at a minimum fluidization rate of at least 0.1 cm / s while exposing the carbon black support to the silicon-containing precursor.

22. The method of claim 20, wherein the method is carried out in a fluidized bed, moving bed, fixed bed, stirred bed or rotary tube furnace.

23. The method according to any one of claims 20-22, wherein the method is carried out in a device that provides uniform concentration and temperature conditions.

24. The method according to any one of claims 20-23, wherein the method is carried out with a Darmque number less than 1 based on particle size, precursor diffusion coefficient in the gas phase, and precursor reaction rate.

25. A method for preparing a silicon-carbon composite, the method comprising: Carbon black carriers are mechanically combined with silicon nanoparticles to form silicon-carbon composites, wherein: The ratio of OAN (oil adsorption value) to BET (Brunauer-Emmett-Teller surface area) of the carbon black carrier is in the range of 1 to 10, wherein OAN is measured by ASTM D2414-23A and BET is measured by ASTM D6556-21. The silicon mass per 100g of carbon black carrier is less than or equal to 0.75%. OAN.

26. The method of claim 25, further comprising mechanically combining carbon nanotubes with the carbon black carrier and silicon nanoparticles.

27. The method of claim 25 or 26, further comprising mechanically combining the binder with the carbon black carrier and the silicon nanoparticles.

28. The method according to any one of claims 25-27, wherein the mechanical combination comprises dry mixing of powders, wet mixing in a slurry, or granulation of powders sprayed with powder.

29. The method according to any one of claims 20-28, wherein the silicon-carbon composite has a D50 volumetric particle size in the range of 5 to 25 micrometers.

30. The method according to any one of claims 20-29, wherein the carbon black carrier has a density of less than or equal to 42. L c Grain size.

31. The method according to any one of claims 20-30, wherein the carbon black carrier contains less than 100 ppm of metallic impurities.

32. The method according to any one of claims 20-31, wherein the carbon black carrier has an OAN in the range of 32 to 400 ml / 100 g carbon.

33. The method according to any one of claims 20-32, wherein the carbon black carrier has a density of 3.2 to 400 μm. 2 BET within the range of / g.

34. The method according to any one of claims 20-33, further comprising adding graphite to the silicon-carbon composite.

35. The method of claim 34, wherein the graphite comprises graphite particles with a particle size of not more than 1 micrometer.

36. The method according to any one of claims 20-35, wherein the carbon black carrier is prepared from carbon black granules.

37. The method according to any one of claims 20-36, wherein the carbon black is graphitized.

38. The method according to any one of claims 20-36, wherein the carbon black is not graphitized.

39. The method according to any one of claims 20-38, wherein the carbon black carrier is an aggregate of carbon black aggregates.

40. The method according to any one of claims 20-39, wherein the silicon in the pores of the silicon-carbon support has the form of discrete, unconnected silicon entities.

41. The method according to any one of claims 20-39, wherein the silicon in the pores of the silicon-carbon support has the form of silicon entities, at least some of which are interconnected.

42. The method according to any one of claims 20-41, wherein the silicon deposited within the pores of the carbon black carrier is in the form of silicon nanoparticles.

43. The method according to any one of claims 20-42, wherein the mass ratio of silicon to carbon in the silicon-carbon composite is between 20:80 and 80:

20.

44. The method according to any one of claims 20-43, further comprising sealing the pores of the silicon-carbon composite.

45. The method according to any one of claims 20-44, further comprising covering the silicon-carbon composite with silicon, carbon, or a combination thereof.

46. ​​The method of claim 45, wherein the silicon-carbon composite is covered by chemical vapor deposition.

47. The method of claim 45, wherein the silicon-carbon composite is coated with carbon by thermal decomposition of a carbon-containing precursor at the surface of the silicon-carbon composite.

48. The method of claim 45, wherein the carbon-containing precursor is sugar, pitch, tar, or sol-gel.

49. The method of claim 45, further comprising sealing the surface pores of the silicon-carbon composite with silicon, followed by carbon coating.

50. The method according to any one of claims 20-49, further comprising reducing the particle size of the carbon support or the silicon-carbon composite.

51. The method according to any one of claims 20-50, further comprising combining the silicon-carbon composite with a LIB anode active material.

52. The method according to any one of claims 20-51, further comprising preparing a LIB anode comprising the silicon-carbon composite.

53. A method for preparing a silicon-carbon composite, the method comprising: Graphite particles with a particle size of no more than 1 micrometer are mechanically combined with silicon nanoparticles to form silicon-carbon structures.

54. The method of claim 53, further comprising covering the silicon-carbon composite with a carbon layer to produce a covered silicon-carbon composite.

55. A silicon-carbon composite prepared according to the method of claim 53 or 54.

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